Electronic apparatus, manufacturing method therefor, and mold device

ABSTRACT

An electronic apparatus such as a portable computer comprises an electronic apparatus frame and a raised portion provided on that region of the electronic apparatus frame which engages an ejector pin projecting from inside a mold device and formed thicker than the other part of the electronic apparatus frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of Application No. PCT/JP99/01764, filedApr. 2, 1999.

[0002] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. 10-173024, filed Jun. 19,1998, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0003] This invention relates to a manufacturing method for anelectronic apparatus frame, and more particularly, to a case where amolded piece is taken out of a mold device.

[0004] Recently, magnesium alloys have been mainly used as the materialof an electronic apparatus frame of a light metal. These alloys aremolded by die-casting or thixotropy. In either of these molding methods,which use different equipment mechanisms, an alloy melted at 580° to750° is injected into a mold device of about 100° to 350° and molded.

[0005]FIG. 1 shows a configuration of a conventional electronicapparatus frame. In this electronic apparatus frame 1, a molten metal isintroduced through a sprue 2, a molten metal inlet portion of a molddevice (which will be described with reference to that portion of thisdrawing which corresponds to the shape of the electronic apparatus framejust molded and the sectional view of FIG. 2 showing the mold device10), and the molten metal is introduced into a desired mold through arunner 3. The introduced molten metal diffuses throughout a cavity 4 andfinally reaches an air vent 5. Further, a molten metal reservoir 6 iscoupled to the air vent 5. When the molten metal is introduced throughthe sprue 2, therefore, air can be discharged to the outside through theair vent 5. Thereupon, the frame can be formed without containing anyvoids therein.

[0006] A molded piece is formed as the molten metal is thus introducedinto the mold device 10. In order to take out the molded piece from thecavity 4, the molded piece is pushed out by means of ejector pins 7.

[0007] In order to enable the molded piece to be pushed out by means ofthe ejector pins 7, the ejector pins 7 are provided in the mold device10, as shown in FIG. 2.

[0008] In the case where a light metal is used as the material of theelectronic apparatus frame 1, the electronic apparatus frame 1 isthinned in general. If a magnesium alloy is the material, the wallthickness of the frame ranges from about 0.7 to 1.0 mm. When the moldedpiece is pushed out of the mold device, therefore, those regions whichare pushed in by means of the ejector pins 7 may be hollowed by the pushforce, possibly leaving push indentations 8 shown in FIG. 3.

[0009] If the electronic apparatus frame 1 is provided with a largenumber of irregularities, such as bosses and ribs, the push forceincreases correspondingly. In some cases, therefore, the pushindentations 8 may be formed more clearly in the pushed regions of theelectronic apparatus frame 1 that is thinned, as mentioned before.

[0010] Such deformation that is attributable to the push force is notlimited to the case of the light metal for use as the material, and isalso caused in the case of a synthetic resin. In the case of thesynthetic resin, the deformation appears as a phenomenon such asblushing.

[0011] If the push indentations 8 or depressions are formed, theexternal appearance is not favorable, and the products are notmass-producible.

[0012] When the ejector pins 7 are pushed in, moreover, not only thepushed regions but also the entire molded piece may possibly subjectedto deformation such as deflection by means of the push force. If suchdeformation occurs, it cannot serve for the utilization of theelectronic apparatus frame 1, and inevitably causes malformation.

BRIEF SUMMARY OF THE INVENTION

[0013] This invention has been contrived in consideration of thesecircumstances, and its object is to provide an electronic apparatushaving a frame that cannot be deformed when it is pushed out of a molddevice by means of ejector pins, a manufacturing method therefor, andthe mold device.

[0014] According to a preferred embodiment, an electronic apparatus ofthis invention comprises a frame and a raised portion provided on thatregion of the frame which engages an ejector pin projecting from insidea mold device and formed thicker than the peripheral portion of theengaging region at the least.

[0015] In a mold device of this invention including a first mold and asecond mold for forming a frame of a metallic material and having anejector pin adapted to push out a molded piece from the first mold afterthe molded piece is formed, moreover, a depression is formed in thatpart of the first mold from which the ejector pin projects so that thepart pushed out by means of the ejector pin forms a raised portion.

[0016] Further, an electronic apparatus manufacturing method of thisinvention for molding an electronic apparatus including a frame of ametallic material by means of a mold device formed having a depressionsuch that a part pushed out by means of an ejector pin forms a raisedportion comprises a flowing process for diffusing a molten metal intothe mold device, a solidifying process for solidifying the molten metalintroduced into the mold device in the flowing process, thereby forminga frame, and an unloading process for pushing out a raised portion of amolded piece formed in the solidifying process, thereby taking out themolded piece from the mold device.

[0017] Additional objects and advantages of the invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0018] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate presently preferredembodiments of the invention, and together with the general descriptiongiven above and the detailed description of the preferred embodimentsgiven below, serve to explain the principles of the invention.

[0019]FIG. 1 is a perspective view showing the shape of a prior artelectronic apparatus frame;

[0020]FIG. 2 is a sectional view showing a configuration of a prior artmold device;

[0021]FIG. 3 is a perspective view showing a state of push indentationsin the prior art electronic apparatus frame;

[0022]FIG. 4 is a perspective view showing the shape of a portablecomputer as an electronic apparatus according to one embodiment of thisembodiment;

[0023]FIG. 5 is a perspective view showing a configuration of anelectronic apparatus frame of the electronic apparatus of the sameembodiment;

[0024]FIG. 6 is a plan view showing the shapes of raised portions andribs of the electronic apparatus frame constituting the electronicapparatus of the same embodiment;

[0025]FIG. 7 is a sectional view showing a configuration of a molddevice of the same embodiment;

[0026]FIGS. 8A and 8B are views showing a manufacturing method for theelectronic apparatus having the electronic apparatus frame of the sameembodiment, in which FIG. 8A is a view showing a state in which a firstmold and a second mold of the mold device are disengaged, and FIG. 8B isa view showing a state in which a molded piece is pushed out of thefirst mold by means of ejector pins;

[0027]FIG. 9 shows a flowchart for the electronic apparatusmanufacturing method of the same embodiment;

[0028]FIG. 10 is a partial sectional view showing a state of anelectronic apparatus frame of an electronic apparatus according to amodification of the present invention and illustrating the formation ofa mound portion;

[0029]FIG. 11 is a partial sectional view showing a state of anelectronic apparatus frame of an electronic apparatus according to amodification of the present invention and illustrating the formation ofa thick-walled portion projecting into the electronic apparatus frame;and

[0030]FIG. 12 is a partial sectional view showing a state of anelectronic apparatus frame of an electronic apparatus according to amodification of the present invention and illustrating the formation ofa thick-walled portion projecting outward from the electronic apparatusframe.

DETAILED DESCRIPTION OF THE INVENTION

[0031] One embodiment of the present invention will now be describedwith reference to FIGS. 4 to 8B.

[0032]FIG. 4 is an external view showing the shape of a portablecomputer 10 such as a note-type personal computer. In this drawing, theportable computer 10 comprises a computer body 11 and a display unit 12that is rockably supported on the computer body 11. The computer body 11is provided with a frame 13, and this frame 13 is design so that a lowerframe 14 and an upper frame 15 are suitably joined by means of, forexample, screws or the like. However, the lower frame 14 and the upperframe 15 may be joined by means of any other arrangement than this.

[0033] In the description to follow, the frame that is applied to theportable computer 10 or some other electronic apparatus will bedescribed as an electronic apparatus frame 20.

[0034]FIG. 5 shows the shape of the electronic apparatus frame 20 thatcannot be deformed even if it is pushed out by means of ejector pins 39according to the present invention. In this drawing, raised portions 21are formed protruding for a given height from the frame body of theelectronic apparatus frame 20, and moreover, ribs 22 that extend ingentle slopes from the top portion of each raised portion 21 toward theperipheral portion are arranged at intervals of, for example, about 90°.FIG. 6 is a plan view of this state taken from the topside.

[0035] A mold device 30 arranged in the following manner is used tomanufacture the electronic apparatus frame 20 having the aforementionedconstruction and prevent the push force of the ejector pins 39 fromcreating push indentations.

[0036] The mold device 30 shown in FIG. 7 is composed of a first mold 31and a second mold 32 that are in engagement with each other, and has acavity 35 formed therein as the first mold 31 and the second mold 32engage each other. In introducing a molten metal into the cavity 35, itis introduced through a sprue 33, a molten metal inlet, and is diffusedby means of a runner 34 so that a substantially parallel molten metalflow is introduced into the cavity 35.

[0037] The molten metal, diffused and introduced by means of the runner34, fills the cavity 35, and is introduced into depressions 36 that areformed in the first mold 31. The depressions 36 are formed by depressingthose regions of the first mold 31 for the ejector pins 39 to a givendepth, and the raised portions 21 are provided on a molded piece 50 asthe molten metal get into the depressions 36 and solidifies.

[0038] If the wall thickness of the electronic apparatus frame 20 rangesfrom about 0.7 to 1.0 mm, for example, the height of projection of theraised portions 21 ranges from about 0.84 to 1.2 mm, which is about 20%greater than the wall thickness of the frame.

[0039] The depressions 36 are located individually on ejector projectionregions 37 in the first mold 31. Through holes 38 are formed in thefirst mold 31 so as to be continuous with the ejector projection regions37, and the ejector pins 39 can get into and out of the through holes38, individually.

[0040] The ejector pins 39 are passed through the through holes 38,individually. The ejector pins 39 are movable along the through holes38. When they project downward, their respective lower end portionsproject from the inner wall surface of the cavity 35 of the first mold31.

[0041] A spring 40 for use as urging means is located on each ejectorpin 39. The springs 40 serve to give urging force to the ejector pins 39so that the pins 39 project from the inner wall surface of the cavity 35of the first mold 31. To apply this urging force, the one-end side ofeach spring 40 is attached to a stationary mold 41. The stationary mold41, which is located above the first mold 31, can be driven in thevertical direction.

[0042] The stationary mold 41 is provided with recesses 42 having agiven size. The recesses 42 are designed to receive the respective upperends of the springs 40. If the stationary mold 42 is driven downward,therefore, corresponding urging force can be applied to the ejector pins39.

[0043] The raised portions 21 are formed on the molded piece 50 as themolten metal flows into the depressions 36. In some cases, however, theraised portions 21 alone may fail to prevent general deformation, suchas deflection, of the electronic apparatus frame 20 when those portionsare pushed in by means of the ejector pins 39. To avoid this, the moldedpiece 50 has the ribs 22 that are arranged at the given angularintervals around the raised portions 21.

[0044] The ribs 22 are in the form of slopes with a sufficient lengththat gently decline from the outer peripheral edge portion of the topportion of each raised portion 21. Since the ribs 22 gently decline fromthe depressions 36, moreover, the molten metal in the depressions 36 caneasily go around.

[0045] Further, the ribs 22 have a length such that the molded piece 50never undergoes deformation such as deflection when the raised portions21 are pressed by means of the ejector pins 39. Furthermore, the lengthof the ribs 22 is restricted in consideration of the attachment of anyother electronic component or the like.

[0046] In order to form these ribs 22 on the molded piece 50, grooves 43corresponding to the ribs 22 are formed around the depressions 36 of themold device 30. The aforesaid ribs 22 can be formed in a manner suchthat the molten metal gets into the grooves 43.

[0047] The molten metal that fills the inside of the cavity 35 reachesan air vent 44 on the other end side of the runner 34 with respect tothe cavity 35. The air vent 44 serves to discharge air in the cavity 35from the cavity 35 to the outside. Thus, the molten metal introducedinto the cavity 35 can prevent generation of voids therein as it reachesa molten metal reservoir 45.

[0048] The following is a description of a method for manufacturing theelectronic apparatus frame 20 by means of the mold device 30 constructedin this manner. This manufacturing method is shown in FIG. 9.

[0049] First, the molten metal is caused to flow into the cavity 35 andfill it (flowing process). Thereafter, the loaded molten metal issolidified by cooling (solidifying process). The molded piece 50 must betaken out of the cavity 35 when it is formed (unloading process).

[0050] Accordingly, the first mold 31 and the second mold 32 must bedisengaged from each other, as shown in FIG. 8A, to allow the moldedpiece 50 to be taken out. When the first mold 31 and the second mold 32are disengaged and opened, however, the molded piece 50 is left adheringto the first mold 31 on the molded piece 50 that is formed having a ribstructure and bosses the electronic apparatus frame 20 usually has orirregularities such as the aforesaid depressions 36 and the ribs 22.

[0051] Therefore, the molded piece 50 in this state expected to be takenout of the first mold 31. To attain this, the molded piece 50 is pushedout by means of the ejector pins 39, as shown in FIG. 8B.

[0052] In this case, the raised portions 21 and the ribs 22 are formedon the molded piece 50 as the molten metal is introduced into the molddevice 30. Since the raised portions 21 and the ribs 22 are provided onthe regions for the projection of the ejector pins 39, however, theraised portions 52 receive the push force of the ejector pins 39 and arepushed out.

[0053] The molded piece 50 can be pushed out of the mold device 30 bymeans of the ejector pins 39 so that it is ready to be removed outward.Since those portions of the molded piece 50 which correspond to thesprue 33 and the runner 34 in the mold device 30 are not disengaged yet,however, they are cut off after the molded piece 50 is taken out. Thus,the electronic apparatus frame 20 is formed.

[0054] According to the manufacturing method for the electronicapparatus frame 20 constructed in this manner and the mold device 30,the engaging portions at which the molded piece 50 is pushed out bymeans of the ejector pins 39 are formed of the raised portions 21. Ifthe push force of the ejector pins 39 is received by means of the raisedportions 21, therefore, the electronic apparatus frame 20 cannot besubjected to any apparent deformation such as depressions if theelectronic apparatus frame 20 is thinned.

[0055] Accordingly, the external appearance of the electronic apparatusframe 20 can be improved, and at the same time, occurrence ofmalformation that is attributable to deformation during the extrusioncan be prevented. Thus, the formation of the raised portions 21 improvesthe efficiency of mass production for the electronic apparatus frame 20.

[0056] Since the ribs 22 are provided at the given angular intervals sothat they extend like gentle slopes from the top portion of each raisedportion 21, moreover, malformation of the electronic apparatus frame 20,such as depression or deflection, can be prevented more securely.

[0057] Since the thinned electronic apparatus frame 20 is reinforced bymeans of the ribs 22, in particular, the general shape of the electronicapparatus frame 20 can be satisfactorily prevented from sufferingdeflection.

[0058] Since the mold device 30 is previously formed having thedepressions 36 and the grooves 43 before the raised portions 21 and theribs 22 are formed, moreover, the molded piece 50 having the raisedportions 21 and the ribs 22 can be formed by only introducing the moltenmetal into the cavity 35 of the mold device 30 and allowing it tosolidify. If the ejector pins 39 are received by means of the raisedportions 21, therefore, the molded piece 50 can be prevented from beingdeformed when the molded piece 50 is removed. Thus, the formation of theelectronic apparatus frame 20 can be improved in efficiency, andtherefore, its cost can be lowered.

[0059] Although the one embodiment of the present invention has beendescribed above, the present invention can be modified variously. Thefollowing is a description of the modification.

[0060] According to the embodiment described above, the raised portions21 are shaped so that their respective top portions are substantiallycircular, as shown in FIGS. 5 and 6. Alternatively, however, the topportion of each raised portion 21 may have a square shape or any othershape.

[0061] Further, the ribs 21 are not limited to the form of gentleslopes, and may be designed so that they extend for a given lengthwithout varying in height, for example.

[0062] Furthermore, the raised portions 21 may be replaced with anyother structures such as protrusions that are formed by mounding thoseportions of the electronic apparatus frame 20 which engage the ejectorpins 39 so that the ejector pins 39 can be caused to abut against theircorresponding mound portions 23, as shown in FIG. 10. In this case, themold device 30 is internally shaped corresponding to this arrangement sothat the mound portions 23 can be e formed by only introducing themolten metal into the mold device 30.

[0063] Further, the mound portions 23 for use as the protrusions may bereplaced with thick-walled portions 24 that are formed on the engagingportions for the ejector pins 39 so as to project into the electronicapparatus frame 20, as shown in FIG. 11. Each thick-walled portion 24includes a top portion 24 a and a slanting portion 24 b that gentlydeclines from the top portion 24 a toward the peripheral portion. Inthis configuration, the slanting portion 24 b serves for reinforcementwhen each ejector pin 39 abuts against the top portion 24 a.

[0064] In FIG. 12, moreover, each thick-walled portion 24 is formedprojecting into the electronic apparatus frame 20. Alternatively,however, a thick-walled portion 25 may be formed projecting outward fromthe electronic apparatus frame 20, as shown in FIG. 11. In this case, asin the aforesaid case, the thick-walled portion 25 has a top portion 25a and a slanting portion 25 b. If a plurality of thick-walled portions25 are formed on the bottom wall surface of the lower frame 14 of theportable computer 10 shown in FIG. 4, for example, the thick-walledportions 25 can be made to function as contact portions to engage a diskor the like.

[0065] Further, various modifications may be effected without departingfrom the spirit of the invention.

[0066] Additional advantages and modifications will readily occur tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details and representativeembodiments shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

What is claimed is:
 1. An electronic apparatus comprising: a frame; anda raised portion provided on that region of said frame which engages anejector pin projecting from inside a mold device and formed thicker thanthe peripheral portion of said engaging region at the least.
 2. Anelectronic apparatus according to claim 1 , wherein said raised portionis surrounded by ribs for reinforcement.
 3. An electronic apparatuscomprising: a frame; and a protrusion provided on that region of saidframe which engages an ejector pin projecting from inside a mold deviceand formed projecting from the peripheral portion of said engagingregion at the least.
 4. In a mold device including a first mold and asecond mold for forming a frame of a metallic material and having anejector pin adapted to push out a molded piece from the first mold afterthe molded piece is formed, a depression being formed in that part ofsaid first mold from which the ejector pin projects so that the partpushed out by means of the ejector pin forms a raised portion.
 5. A molddevice according to claim 4 , wherein said depression is surrounded bygrooves for forming ribs for reinforcement.
 6. A method of manufacturingan electronic apparatus, comprising the steps of: introducing moltenmetal into a mold having a first mold section and a second mold section,said first mold section has a recess so that a molding has a thick-wallpart that may contact an ejector pin; solidifying the molten metal inthe mold, thereby to form a molding; and pushing the thick-wall part ofthe molding with the ejector pin, thereby to take the molding from themold.